Using atmosphere-induced changes in the radio signals, scientists will infer the state of the atmosphere above some 3,000 locations every 24 hours, including vast stretches of ocean inadequately profiled by current satellites and other tools.

Nearly 100 scientists from over a dozen countries are meeting in Boulder on August 21–23 to help plan the use of data from this $100 million mission, which will begin operations in 2005.

Called COSMIC, the satellite network is now being developed through a U.S.-Taiwan partnership based on a system design provided by the University Corporation for Atmospheric Research, where the COSMIC Project Office is based. Taiwan’s National Science Council and National Space Program Office (NSPO) and the U.S. National Science Foundation are providing primary support for COSMIC.

With six satellite receivers, COSMIC will collect a global, 3-D data set expected to improve analyses of both weather and climate change. By tracking temperature in the upper atmosphere up to 30 miles high, COSMIC could help clarify whether these regions are cooling due to heat-trapping greenhouse gases closer to the surface.

COSMIC will also measure high-altitude electron density, potentially enhancing forecasts of ionospheric activity and “space weather”. Its satellites will probe the atmosphere using radio occultation, a technique developed in the 1960s to study other planets but more recently applied to Earth’s atmosphere.

Each satellite will intercept a GPS signal after it passes through (is occulted by) the atmosphere close to the horizon. Such a path brings the signal through a deep cross-section of the atmosphere. Variations in electron density, air density, temperature, and moisture bend the signal and change its speed.